Television



April 7, 1931- H. P. DONLE I 7 1,800,057

' I TELEVISION Filed Dec. 26. 1928 2 Sheets-Sheet 1 AMPA/HE? 240/0 1956. fEl/YSM/F/Z'R 1 I d AMI-"L mi? AMPL lF/ER April 1931- H. P. DONLE 1,300,057

TELEVISIQN Filed Dec. 26, 1928 2 Sheets-Sheet 2 Patented Apr. 7, 1931 UNITED STATES nanom: 2. zoom, on

MEBIDEN, C ON'NEGTIGUT, ASBIGNOB TO RADIO INVENTIOHS,

INC., A CORPORATION OF NEW YORK rannvrsron Application filed December bodiment of the invention will be found set forth hereinafter.

In the form shown a receivin scanning member is in the form of a disc avin the light apertures arran ed spirally at uni orm intervals. Instead this spiral makes two or more turns. In the discs ordinarily employed there are usually either 24 or 48 holes in a singleturn or circumference so that in a 24 hole disc the suc- 25 cessive holes are arranged at intervals of 15 and in a 48 hole disc they would be arranged at intervals of 7 In the form shown herein the apertures are spaced apart and by distributing these apertures throughout four turns, I provide a receivin disc which can he; synchronized with a 48 ole transmitting sc. This receiving disc is accordingly rotated at four times the angular speed of the transmitting disc. It is apparent therefore that thisseries of 48 holes can be made to pass by the frame or observation position in the same length of time that the 48 holes of the ordie nary disc would take. The result would be that a light image would be visible simultaneously from one of the apertures in each turn. To' revent this the shutter member which is madb of suitable opa ue material has a number of slots each of w ich is in the form of a spiral whose shortest radius is shghtly less a single turn of 360 2B, 1828. Serial 828,837.

than the shortest radius to the apertures of the scanning disc to ermit the innermost aperture to register wit the inner edge of the slot. The greatest radius of the slot is slightly greater than the radius to the outer scan- 50 ning aperture so that the outer aperture can be brought into alignment with the outer edge of the slot. In other words, the radial dimension, relative to the disk centre, of the area exposed by the passa e of one of these slots past a fixed point wi 1 be not less than the difference of radial mensuration of the first and last aperture of the multi-spiral scanning disk.

I have shown three of these shutter slots and the gear ratio between the scanning disc and the shutter disc is such that the shutter rotates at one-twelfth the speed of the scanning disc. In other words there are four revolutions of the scanning disc for one cycleof shutter apertures. The result is that for a given diameter of scanning disc the observation frame can be approximately sixteen times the area of the. corresponding frame of the usual scanning disc.

To synchronize the scanning disc with the transmitting disc I may employ the ,construction of my former application #306,390, filed Sept. 17 1928, or that of my application #322,360, filed November 28, 1928.

In the construction here shown I illustrate the device of the earlier application for convenience. I i

Fig. lis a diagrammatic view of transmitting and receiving apparatus embodying my invention.

Fig.2 is a .face view of the transmitting scanning disc.

Fig. 3'is a face view of the receiving scanning disc. 7

Fig. 4 is a face view of the shutter used with the scannerof Fig. 3.

Fig. 5 is a front view of the receiving a paratus showing the observation opening in The picture source or image to be trans-- mitted is diagrammatically indicated at 10 and may of course represent an actual stationary or moving ob ect or a moving film. The transmitting scanner 11 is driven by a suitable motor 12 and provided with one or more series usually one of apertures 13 arranged spirally (48 are shown herein) and through which the light from the imagepass'es to a light sensitive cell 14. The output of this cell preferably passes through an amplifier 15 and a radio frequency transmitting device 16 provided with a suitable output antenna 17 and so forth.

At the receiving end is located a suitable pick-up antenna 18, and radio receivin and amplifying means 19. The output 0 this receiver is connected to a suitable light source 20 such as a so-called neon lamp. 1

The scanning disc 21 at the, receiving end is light in weight and provided with a series of apertures 22 corresponding with the apertures 13 in the transmitter disc and is driven by a motor 23 of any suitable type at a speed such that each successive aperture 22 will synchronize with the apertures 13 and the image will accordingly be visible at 24 either on a screen or through a lens or in a frame as usual in systems of this character.

The synchronizing of the disc 21 with the disc '11 is accomplished through an electromagnetic system utilizing light actuating impulses derived from the transmitting station immediately after the passage of each line scanning aperture across the field of view, by suitable design of the transmitter. Attached to or rotatable with the receiving disc 21 is an armature plate or disc 25 of steel having bars '26, corresponding to the radial lines of apertures 22. A number of magnets or field coils 27 are preferably arranged to correspond with the number ofarmature bars 26 (or one half as many). The coils of these magnets are connected to the audio amplifier 28 which in turn is arranged in shunt with a resistance 29 in the receiving circuit.

When a signal impulse is received the grid of the last amplifier tube-in .28 is charged negatively thus allowing only a small late current to flow hrough the amplifier. en the current through the lamp 20 isreduced to the minimum va ue this negative charge is greatly reduced and a large current flows through the plate circuit and the field coils 27 thus energizing the latter.

The result of this arrangement is that when the reproducing disc 21 is rotating in the bars or arms 26 of the rotating armature attached to the reproducing disc 21. This in effect locks the disc 21 in exact synchronism with the transmitting disc 11 which will be maintained throughout a wide variation in speed of the transmitter disc due to the lockin action of this device.

The shutter 30, in the form shown, is provided with three slots'31, all of which are alike and which are spaced at uniform intervals. Each slot is of a general spiral shape and so proportioned and placed that every two circumferentially adjacent apertures of a spiral will be partially uncovered simultaneously once during a complete passage of one shutter slot. The scanning disc 21 is mounted directly on the shaft 22 of the motor 23 so that they rotate at the same speed. The

shutter 30 is secured to a sleeve 33 which is rotatably mounted on the same shaft so that the two discs are co-axiallyrotatable. The transmission gears 34, 35, 36 and 37 are designed to produce a ratio of 12 to 1 so that the scanning disc rotates 1 2 times as fast as the shutter. The face plate 38 has an observation opening 39 whose width represents ap-v proximately the circumferential space between the adjacent radial lines of apertures 22. The radial height of this opening 39 is approximately the same as the greatest radial dimension of the spiral set of apertures 22. At every point the shutter slot 31 is so proportioned relative to the spacings of the apertures 22 uncovered by it, that two adjacent apertures are always partially uncovered simultaneously. This means that the effective circumferential width of each shutter slot is gradually reduced as the radius is decreased.

The ends of the spiral slots are so tapered off that only one total aperture is visible at any instant, which total aperture may be made up of a portion of the aperture leaving the field of view and another portion of the aperture centering the field, as shown in Fig. 5 by the first and last apertures of the spiral series.

The result isthat we are able to produce by the use of this invention a picture whose area is approximately 16 times the area of a picture produced by a scanning disc of the same diameter and utilizing the usual single turn spiral group of apertures.

Although this invention is primarily intended for radio transmission and reception,

certain features may be used in wire transmission as set forth in my application Number 322,360 above referred to.

Itshould also be understood that the scanning and shutter combination may be used with the synchronizer of said application $322,360 wherein the energy of the sync ronizing impulse is independent of the li ht' intensity of the picture source and in act may be kept in step with the transmitter even when the picture is cut off,

I claim:

I. A television apparatus comprising. a scanning disc having spirall disposed apertures, a shutter mounted on t e same axis and having spirally disposed slots whose angular length is less than 360 degrees and means for rotating the disc and shutter at difierent relative speeds.

2. A television scanning apparatus comprisingra disc having apertures arranged in a plurality of spiral convolutions, a coo rating shutter d1sc having spiral slots 0 an effective angular width gradually increasing from the inner to the outer end of the spiral, means for rotating the 'two discs at different relative speeds so as to analyze a television signal.

3. Television apparatus including a rotary scanning member, having a plurality of convolutions of spirally disposed light apertures, and a'shutter member having spirally disposed tapering slots, and means for difierentially rotating these two members at definitely related speeds. r

4. Television apparatus comprising a scanning member having a number of rows of apertures and a shutter member having a plurality of discrete slots, each of which angularly overlaps the adjacent slots, and coactmg with the scannin member, and means to rotate these mem ers at relative speeds to expose the whole of no more than one scanning aperture at any instant.

5. A television scanning method wherein a disc-having a plurality of convolutions of apertures coacts with a second disc having slots of a radial width substantially greater than that of a single aperture and covering less than 360 degrees of angular length, so that each aperture in turn is exposed thru -a single slot, during one complete analysis of a television signal.

6. In television scanning apparatus employing a scanning member having a multispiral arrangement of apertures, a coacting shutter disc with a plurality of taper slots,

each of which is less than 360 degrees in angular length.

7 In television scanning apparatus, the

combination of a disc having apertures, ar-

ranged in a spiral of more than 360 degrees, with a shutter disc havin slots arranged in a plurality of spirals, eac spiral having an angular length of less than 360 degrees.

HAROLD P. DONLE.

I my 

